Police said their four-legged hero absorbed a blow to the head over the weekend from a Metro bus driver in front of a group of children but didn't lose his cool, according to the Washington Examiner.

McGruff, who was actually District officer Tyrone Hardy in costume, was handing out flyers to kids in northwest Washington Saturday when bus driver Shawn Brim, 38, stopped, got out and adjusted his mirrors and then cold-cocked McGruff in the head with a closed fist, according to a police report.

A woozy McGruff staggered. Kids screamed. The alleged attacker hopped back on his bus and drove off.

Other police officers who were there with McGruff and watched the alleged assault quickly tracked down the bus and the driver.

Brim, 38, later told a supervisor that he was trying “to be funny,” Metro spokeswoman Candace Smith told The Examiner on Monday.